An aircraft typically follows a constant glide slope as it approaches an airport. The aircraft is equipped with autopilots, which provide delta torque commands that adjust the engine torques of corresponding engines to keep the aircraft on a constant glide slope. However, the engine torques are changed without regard to resulting changes in airspeed. Thus, the aircraft can undergo large fluctuations in airspeed during approach.
To maintain both constant glide slope and air speed, a pilot must continually adjust engine power. This entails significant pilot workload.